Optical properties and aging of light-absorbing secondary organic aerosol

Liu, Jiumeng; Lin, Peng; Laskin, Alexander; Laskin, Julia; Kathmann, Shawn M.; Wise, Matthew E.; Caylor, R.; Imholt, Felisha; Selimovic, Vanessa; Shilling, John E.

doi:10.5194/acp-16-12815-2016

Cited by 173 publications

(210 citation statements)

References 91 publications

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“…All of the organic aerosols were assumed to have the same optical properties in CRTM and RM, which is obviously an approximate assumption. Liu et al (2016) show that SOA optical properties could be highly varied depending on the chemical species, aging time and ambient NO x concentrations. Both CRTM and RM assume that all aerosols are externally mixed, which may not best fit the situation in the real world.…”

Section: Discussionmentioning

confidence: 99%

A case study of aerosol data assimilation with the Community Multi-scale Air Quality Model over the contiguous United States using 3D-Var and optimal interpolation methods

et al. 2017

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Abstract. This study applies the Gridpoint Statistical Interpolation (GSI) 3D-Var assimilation tool originally developed by the National Centers for Environmental Prediction (NCEP), to improve surface PM 2.5 predictions over the contiguous United States (CONUS) by assimilating aerosol optical depth (AOD) and surface PM 2.5 in version 5.1 of the Community Multi-scale Air Quality (CMAQ) modeling system. An optimal interpolation (OI) method implemented earlier (Tang et al., 2015) for the CMAQ modeling system is also tested for the same period (July 2011) over the same CONUS. Both GSI and OI methods assimilate surface PM 2.5 observations at 00:00, 06:00, 12:00 and 18:00 UTC, and MODIS AOD at 18:00 UTC. The assimilations of observations using both GSI and OI generally help reduce the prediction biases and improve correlation between model predictions and observations. In the GSI experiments, assimilation of surface PM 2.5 (particle matter with diameter < 2.5 µm) leads to stronger increments in surface PM 2.5 compared to its MODIS AOD assimilation at the 550 nm wavelength. In contrast, we find a stronger OI impact of the MODIS AOD on surface aerosols at 18:00 UTC compared to the surface PM 2.5 OI method. GSI produces smoother result and yields overall better correlation coefficient and root mean squared error (RMSE). It should be noted that the 3D-Var and OI methods used here have several big differences besides the data assimilation schemes. For instance, the OI uses relatively big model uncertainties, which helps yield smaller mean biases, but sometimes causes the RMSE to increase. We also examine and discuss the sensitivity of the assimilation experiments' results to the AOD forward operators.

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Section: Discussionmentioning

confidence: 99%

A case study of aerosol data assimilation with the Community Multi-scale Air Quality Model over the contiguous United States using 3D-Var and optimal interpolation methods

et al. 2017

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“…The effect of NO x on the formation of SOA has been highly debated and not sufficiently explored to date. However, experimental chamber studies with representative precursors (Kleindienst et al, 2004;J. Liu et al, 2016) and model estimates based on ambient measurements (Henze et al, 2008) provide compelling evidence in favor of increasing SOA yields in the presence of NO x .…”

Section: Effect Of No X On Aged Aerosolmentioning

confidence: 99%

Light absorption by polar and non-polar aerosol compounds from laboratory biomass combustion

et al. 2018

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Abstract. Fresh and atmospherically aged biomass-burning (BB) aerosol mass is mostly comprised of strongly lightabsorbing black carbon (BC) and of organic carbon (OC) with its light-absorbing fraction -brown carbon (BrC). There is a lack of data on the physical and chemical properties of atmospheric BB aerosols, leading to high uncertainties in estimates of the BB impact on air quality and climate, especially for BrC. The polarity of chemical compounds influences their fate in the atmosphere including wet/dry deposition and chemical and physical processing. So far, most of the attention has been given to the water-soluble (polar) fraction of BrC, while the non-polar BrC fraction has been largely ignored. In the present study, the light absorption properties of polar and non-polar fractions of fresh and aged BB emissions were examined to estimate the contribution of differentpolarity organic compounds to the light absorption properties of BB aerosols.In our experiments, four globally and regionally important fuels were burned under flaming and smoldering conditions in the Desert Research Institute (DRI) combustion chamber. To mimic atmospheric oxidation processes (5-7 days), BB emissions were aged using an oxidation flow reactor (OFR). Fresh and OFR-aged BB aerosols were collected on filters and extracted with water and hexane to study absorption properties of polar and non-polar organic species. Results of spectrophotometric measurements (absorption weighted by the solar spectrum and normalized to mass of fuel consumed) over the 190 to 900 nm wavelength range showed that the non-polar (hexane-soluble) fraction is 2-3 times more absorbing than the polar (water-soluble) fraction. However, for emissions from fuels that undergo flaming combustion, an increased absorbance was observed for the water extracts of oxidized/aged emissions while the absorption of the hexane extracts was lower for the aged emissions for the same type of fuels. Absorption Ångström exponent (AAE) values, computed based on absorbance values from spectrophotometer measurements, were changed with aging and the nature of this change was fuel dependent. The light absorption by humic-like substances (HULIS) was found to be higher in fuels characteristic of the southwestern USA. The absorption of the HULIS fraction was lower for OFR-aged BB emissions. Comparison of the light absorption properties of different-polarity extracts (water, hexane, HULIS) provides insight into the chemical nature of BB BrC and its transformation during oxidation processes.

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“…The presence of NO x may lead to the formation of nitrogen-containing aromatic compounds during aerosol aging (Kahnt et al, 2013;Kitanovski et al, 2012). These compounds can absorb in the 450 -550 nm range (Liu et al, 2016b) and therefore, can cause an absorbance increase in this spectral range. High NO x emissions observed during the combustion of FASMEE and Hawken fire fuels may be explained by two phenomena: elemental 25 composition of fuel and high temperature burning conditions.…”

Section: Absorbance Of Polar and Non-polar Fractionsmentioning

confidence: 99%

“…Previous studies on the evolution of SOA in the presence of NO x was mostly focused on total SOA yields, without investigating light absorption properties and compositional variability. Recently, (Liu et al, 2016b) estimated the effect of 15 photochemical aging in the presence of NO x on light absorption properties of aerosols produced from different primary OA precursors. They reported a large increase in the MAC values in the 300 to 500 nm wavelength range for SOA derived from aromatic precursors in a NO x -rich environment compared to NO x -free conditions.…”

Section: Absorbance Of Polar and Non-polar Fractionsmentioning

confidence: 99%

Light absorption by polar and non-polar aerosol compounds from laboratory biomass combustion

Sengupta¹,

Samburova²,

Bhattarai³

et al. 2018

Preprint

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Abstract. Fresh and atmospherically aged biomass-burning (BB) aerosol mass is mostly comprised of black carbon (BC) and organic carbon (OC) with its light-absorbing fraction -brown carbon (BrC). 10There is a lack of data on the physical and chemical properties of atmospheric BB aerosols, leading to high uncertainties in estimates of the BB impact on air quality and climate, especially for BrC. The polarity of chemical compounds influences their fate in the atmosphere including wet/dry deposition and chemical and physical processing. So far, most of the attention has been given to the water-soluble (polar) fraction of BrC, while the non-polar BrC fraction has been largely ignored. In the present study, 15 the light absorption properties of polar and non-polar fractions of fresh and aged BB emissions were examined to estimate the contribution of different-polarity organic compounds to the light absorption properties of BB aerosols.In our experiments, four globally and regionally important fuels were burned under flaming and smoldering conditions in DRI's combustion chamber. To mimic atmospheric oxidation processes (5-7 20 days), BB emissions were aged using an oxidation flow reactor (OFR). Fresh and OFR-aged BB aerosols were collected on filters and extracted with water and hexane to study absorption properties of polar and non-polar organic species. Spectrophotometric measurements over the 190 to 900 nm wavelength range showed that the non-polar (hexane-soluble) fraction is 2-3 times more absorbing than the polar (water-soluble) fraction. However, an increased absorbance was observed for the water 25 extracts of oxidized/aged emissions while the absorption of the hexane extracts was lower for the aged emissions. Comparing the absorption Ångström Exponent (AAE) values, we observed changes in the light absorption properties of BB aerosols with aging that was dependent on the fuel types. The light Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2018-161 Manuscript under review for journal Atmos. Chem. Phys.

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Optical properties and aging of light-absorbing secondary organic aerosol

Cited by 173 publications

References 91 publications

A case study of aerosol data assimilation with the Community Multi-scale Air Quality Model over the contiguous United States using 3D-Var and optimal interpolation methods

A case study of aerosol data assimilation with the Community Multi-scale Air Quality Model over the contiguous United States using 3D-Var and optimal interpolation methods

Light absorption by polar and non-polar aerosol compounds from laboratory biomass combustion

Light absorption by polar and non-polar aerosol compounds from laboratory biomass combustion

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